Inflatable prefabricated structure



Jan. 4, 1966 w, sc 3,227,169

INFLATABLE PREFABRI CATED STRUCTURE Original Filed Feb. 8, 1963 3 Sheets-Sheet l INVENTOR Mu MM fi flaw/5A Jan. 4, 1966 w. H. FISCHER INFLATABLE PREFABRICATED STRUCTURE 3 Sheets-Sheet 2 Original Filed Feb. 8, 1965 1 VENTOR W/u. MM hf H5015? ATTOAA/fYS 1956 w. H. FISCHER 3,

INFLATABLE PREFABRICATED STRUCTURE original Filed Feb. 8, 1965 3 Sheets-Sheet 5 *1? b j. "1 f h 1 ,4

' INVENTOR WIA 1 MM fisc/m? BY Xb 154A ATTORNEYS United States Patent 3 227 169 INFLATABLE ranrhsiircarnn STRUCTURE William H. Fischer, Redding, Conn., assignor to Air Inflatable Products Corporation, a corporation of Delaware Original application Feb. 8, 1963, Ser. No. 257,314.

Divided and this application Oct. 12, 1964, Ser. No. 403,297

9 Claims. (Cl. 135-4) This invention relates to inflatable transportable structures, and more particularly to prefabricated enclosures which may be quickly erected by inflation at the site. This application is a division of my copending application S.N.

257,314 filed February 8, 1963.

Temporary prefabricated structures such as inflatable radome enclosures for radar or communication antennas present serious problems of weakness under wind loading, erection difiiculties, and the need for constant pressurizing .of the entire interior of the structure, requiring doubledoor air-locks or the like to maintain internal pressure.

Inflatable single-skin balloon-like radomes possess the structural strength to support their own weight when inflated, but extreme loading conditions presented by high wind loads often cause the failure of such structures, since they possess very little structural stiflness and rigidity.

Prior art inflated radomes require considerable sealing and caulking around the juncture of the tower and radome base and around the air-lock and air-lock doors, in order to maintain their inflated shape.

Single-skin prior art radomes are also subject to tearing or ripping on the radar or communications antennas during high winds. This is a particularly serious problem if there is dimpling of the radorne skin so that it catches on a rotating radar reflector, for example. When such a tear occurs, the radome skin generally splits from top to bottom as air pressure rushes through the break; .The ripped radome skin then clings to the radar reflector and acts as a large sail. In high winds the radar may be swept from the radar tower and destroyed.

The prefabricated structures of the present invention provide unusually high strength coupled with unexpected convenience during handling and erection of the structures. They incorporate a unique construction taking advantage of a double Walled inflatable cellular panel arrangement.

is no great rush of air through the break. This is due to .the bathing structure between each cellular chamber in the The break can be easily patched over the low panels. velocity air issuing from the disrupted cellular chamber. Thus a break in a panel wall does not endanger the whole "structure and the equipment it houses, since there is ample time to patch the break.

Accordingly it is a principal object of this invention to provide lightweight structures which may be fabricated, transported and erected with maximum convenience.

Another object of the invention is to provide prefabrilcated enclosures of the above character affording high hereinafter set forth, and the scope of the invention will be indicated in the claims.

The panels may be conveniently fabricated .and transported to the erection site, where their handling and inflation is greatly simplified by their unusual construction. In the event of a tear in a cellular panel, there pitch as indicated in FIGURE 3.

Patented Jan. 4, 1966 fabricated enclosure incorporating the present invention.

FIGURE 2 is an enlarged fragmentary view of the interpanel locked seam construction of the enclosureillustrated in FIGURE 1.

FIGURE 3 is a further enlarged fragmentary elevation view of the sector panel locking elements shown in FIGURE 2.

FIGURES 4 and 5 are top and plan views respectively showing the elements of FIGURE 3 intheir unlocked and locked juxtapositions.

FIGURES 6 and 7 are enlarged sectional end elevation views showing the woven fabric forming the internal and external skins of the structures of the invention in successive stages of their fabrication.

FIGURE 8 is an enlarged fragmentary perspective view showing a cross-section of the wall of the enclosure illustrated in FIGURE '1.

FIGURE 9 is a perspective view showing one compound curved panel forming a portion of the enclosure illustrated in FIGURE 1.

FIGURE 10 is a plan view of two web elements shown in FIGURE 8, and

FIGURE 11 is a greatly enlarged fragmentary crosssectional perspective view of the structure shown in FIG- URE18 broken away to show the construction details more clear y.

Similar reference characters refer to similar parts throughout the several views of the drawings.

FIGURE 1 shows a prefabricated structure incorporating the present invention, in the form of a cylindrical, round-topped, beehive-shaped enclosure generally indicated at 20. This structure is formed of six compoundcurved inflatable panels 28 or 30 having the general appearance of the panel 28 shown in FIGURE 9. All of these doubly-curved panels are formed of two generally parallel walls or skins of substantially air-impervious material, spaced apart as shown in FIGURES 8 and 11 by a number of web elements bridging the intervening space and contributing form and shape to the resulting structure upon inflation. Compressed air under low pressure is introduced into the spaces between the two outer skins, producing inflation of the panels illustrated in FIG- URE 9, and these panels are firmly locked together along their juxtaposed edges by the locking elements illustrated in FIGURES 2-5.

As indicated in FIGURE 1, the structure 20 is anchored in position at its site by a large plurality of guys 22 securing its lower periphery to embedded stakes 24. The guys 22 are joined to the inflatable enclosure 20 by attachment to the successive peaks of the scalloped guy flaps 26, integrally joined to the lower periphery of each of the panels 28 and 30 which fit together to form the complete structure 20.

The inflatable sector panel 39 differs from the panel 28 only in the presence of an entrance portal 32 incorporating closable mating flaps 34 spanning the portal 32. Otherwise the entrance panel 3%) closely resembles the unapertured panels 28 comprising the remainder of the structure 20.

The separate gore-like panels 23 and 30 are firmly locked together along their juxtaposed curved edges 36 by lock flaps or hands 38 having one edge shaped in a scalloped configuration presenting outwardly projecting peaks 4%), shown in FIGURE 2, each having a helical lock 42 protruding therefrom and which may be matingly interleaved with a corresponding helical lock 44 of opposite The helical wire-shaped lock members are firmly anchored to the peaks 40 by clamps 46 riveted in position flanking a nylon bearing block 48, and a bolt rope 49 integrally joined along the curved or scalloped edge of the flap 38 may pass between the clamp 45 and the bearing block 48 to transmit its tension directly to the helical lock members 42 and 44.

As shown in FIGURES 4 and 5, the lock members 42 and 44 are easily interfitted over a portion of their curved peripheries by interleaving the turns of the facing oppositely pitched helical lock members, and a lock wire 59 is then inserted to retain the interleaved helices in their locked engagement. The lock members 42 and 44 and the riveted clamps 46 are preferably formed of weatherproof stainless steel, extending the useful life of the structure 20.

The successive steps in the fabrication of the panels 28 and 30 are shown in FIGURES 6, 7 and 11. The first step in the fabrication of the sector panels 28 is the weaving of a double layer sheet of fabric 52 having an upper layer 54 and a lower layer 56, these layers being integrally interwoven at a series of predetermined spaced junction lines extending across the entire loomed width of the double layer fabric, which may extend to 54 inches or more. The length of the interwoven junction lines 58 over which the separate panels 54 and 56 are integrally interwoven may be any desired number of fiber diameters, with preferably or 12 or even more fiber diameters being incorporated in each interwoven junction 58. The space between each of the adjacent interwoven junctions 58 is predetermined, to provide the desired curvature in the panel ultimately fabricated therefrom, as will be more fully explained below.

The next successive steps in the fabrication of the panel 28 are illustrated in FIGURE 7, where each span of the lower layer 56 is shown cut away with the central strip 60 being removed to leave integral tabs 62 protruding from the junctions 58 along one side of the woven sheet material 52. A layer of impregnated air-impervious sheet material 65, which may be neoprene-impregnated Dacron fabric, for example, is cemented to the entire surface of the sheet 52 on the opposite side from the protruding tabs 62. The formation of the double-skinned inflatable panel 28 is illustrated in FIGURES 8 and 11, where the outer wall layer 52 is positioned with its protruding tab 62 facing a similar inner sheet 52a having similar tabs likewise facing the tabs on the opposed sheet 52.

A series of web panels 64 have their elongated opposite edges sandwiched between and firmly cemented to the tabs 62 protruding from each junction 58 on each of the facing wall sheets 52 and 52:: as shown in FIGURE 8. The enlarged fragmentary view of FIGURE 11 shows the successive steps in the construction of the cellular inflatable panel 28, beginning at the upper portion of this figure, where the protruding tabs 62 are shown fanned apart and ready to receive a web panel 64. In the center of FIGURE 11 the web 64 is shown in position, with its elongated edge 66 projecting between the fanned apart protruding tabs 62. The near edge 68 of the web panel 64 has the corresponding tabs 62 of the fabric sheet 52a firmly cemented down on its opposite sides to sandwich and bond the web 64 firmly to the fabric sheet 52a along the junction 58.

A completed sandwiched web construction is illustrated toward the bottom of FIGURE 11 where both elongated edges of another web 64 are shown sandwich-bonded between the respective tabs 62 protruding inwardly from the facing junctions 53 of the respective panels 52 and 52a. The resulting bonded webs 64 define with the facing fabric panels 52 and 52a a series of successive longitudinally elongated air chambers 70. The web 64 may be porous and permeable to air passing between adjacent chambers 76, and these chambers may also be connected by end passages not shown on the drawings for convenient inflation of the completed panel member 28.

The compound curvature of the final fabricated panel 28, best shown in FIGURE 9, is produced by the dimensioning of the respective components of the structure. As indicated in FIGURE 8, the generally vertical or right circular cylindrical lower portion of the panel 28 is produced by spacing the parallel junction lines 58 of the inner fabric panel 52a successive equal distances apart, these distances being the same as the distances between the cor responding junction lines 58 on the facing outer panels 52. Thus both inner and outer walls of the lower chambers 7% are of equal height, and the lower or right circular cylindrical portion 72 of the panel 28 is curved only in a single direction, about a vertical axis. This curvature is determined by the radius of curvature of the curved elongated edges of the webs 64a, shown in top plan view in FIGURE 10.

By contrast the compound curvature of the upper, arched section 74 of the panel 28 is produced by moving the junction lines 58 on the inner panel 52a successively closer together over this upper portion of the panel. By this means the upper chambers 70!) have their outer walls slightly taller than their inner walls, providing successive angular displacement of the successive webs 641) over the upper portion of the panel 28, producing the inward leaning configuration of the completed panel. This curvature about a generally horizontal axis is combined with sharper curvature at a diminishing radius about a vertical axis with successive and more sharply curved web 6415, as shown in FIGURE 10, where the curvature and radius of curvature of an upper web 64b may be compared with those of a lower web 64a.

The successive and more sharply curved webs combined with the diminished relative height of the inner walls of the chambers 7%]; produces the arched compound curvature illustrated in FIGURE 9, permitting the successive panels 28 and 3% to be joined along the abutting edges 36 to form the completed structure of FIGURE 1.

If the progressive variations in the curvature of the web 64 and the respective heights of the inner and outer walls of the chambers 70b are generally uniform, the smooth curvature illustrated in FIGURES 1 and 9 will result. Non-uniform rates of variation of these variables will produce non-uniform curved surfaces which may if desired produce a sharp edged contour comparable to the hard chine of fiat-bottomed and V-bottomcd boats, as contrasted with the smoothly curving hull surfaces and profiles of an hour-glass shaped, deep-keel sailboat hull.

The panels 28 are preferably made of weather resistant impregnated Dacron fabrics, woven in the double layers shown in FIGURE 6 and subjected to a heat setting treatment for cleaning and preshrinking the fabric prior to the fabrication steps described above. The layer 65 may be formed of closely woven nylon or Dacron fabric, preferably coated on both sides with one or more thinly doctored layers of neoprene or vinyl material, thus impregnating this outer layer 65 to enhance air retention, strength and abrasion resistance of the resulting structure. These impregnating materials are generally applied in solvent solutions from which the solvent is evaporated by heat during the coating process to leave the dry impregnated fabric ready for the fabrication of the panels 28.

After the removal of the central strip 60 to leave the protruding tabs 62, these tabs 62 and if desired the adjacent surface of the fabric sheet 52 is covered with a thin coating of neoprene-solvent solution to fill the interstices of the tabs 62, stiffening or sizing these tabs for subsequent use and priming the tabs to produce a firmer bond sandwiching the panel 64 between the mating tabs 62.

Automatic processing equipment is easily adapted to produce the desired radius of curvature for each of the web panels 64 and the loom on which the double layer fabric panels 52 are woven can be adjusted to space the junctions 58 successively closer together at the precise predetermined distances required to produce the desired curvature of the resulting panels 28.

To maintain the position orientation of the components, afmatch mark system of successive marks spaced at small intervals, such as 3 inches or 6 :inches, along the mating edges of the fabric will facilitate the desired registration of the component elements.

The successively piled, horizontal orientation of the or knotting of the panel as it inflates to its erect position.

The inflatable enclosures ofthepresent invention are well adapted for convenient erection in as short a period as three hours by a practiced team of erectors, and they may be dismantled with equal case. These structures require low pressures of less than one pound per square inch to raise them to their erect position, and an internal inflation pressure less than 2 psi. will stiffen the resulti'ng-structure to withstand wind loadings produced by hurricane force winds of 100 miles per hour..

The extremely lightweight structure illustrated in FIG- "UREl, '43 feet high and 43 feet in diameter, is formed of 6 panels each weighing less than 300 pounds and producing a total structure weight of only 1,700 pounds. This flexible enclosure, with its panels inflated and locked together in the manner shown in FIGURES 1 and 2, is capable of supporting a 2,000 pound weight suspended inside the center of its dome.

While a more airtight wall can be made by adding additional layers 65 to one or both walls of the panels 28, the addition of this extra weight is preferably eliminated by providing an air compressor 76 connected to supply additional compressed air to the panels whenever required, at the command of pressure sensitive limit switches 78, as shown in FIGURE 9.

The desired objectives of convenience in fabrication, transportation and erection are thus combined with extremely lightweight, structural rigidity and stiffness to provide temporary or semi-permanent prefabricated structures and enclosures which are well adapted to provide shelter for men and equipment under severe adverse conditions of wind and weather. The absorption or reflection of external radiation may be controlled by the incorporation of metallized or vapor deposited layers of aluminum in one or both of the surface walls of the panels 28 to produce Thermos bottle or greenhouse effects as desired. While the interior of the resulting structures need not be pressurized to provide structural rigidity, breathable atmospheres may be maintained at the desired pressures, higher than any rarified atmospheres outside the structure if desired.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction-s without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which, as a matter of language, might be said to fall therebetween.

I claim:

1. A sel'fasuppo-rting prefabricated double walled inflatable structure comprising in combination (A) a plurality of curved sector panels each having an inner wall and an outer wall;

(B) a plurality of junction lines extending transversely across each said wall, with the width of said outer wall being greater than the corresponding width of said inner wall along each junction line,

(C) bothsaid walls having juxtaposed tabs secured along said junction lines, each of said juxtaposed tabs being joined together to join said walls in spaced relationship along said junction lines,

(D) end closure means joining the peripheries of said inner wall and said outer wall and forming with the facing surfaces of said inner wall and said outer wall a successively arrayed plurality of adjoining longitudinally-curved inflatable cell chambers joined to form a cellular double-walled inflatable sector panel having an arcuately curved shape upon inflation,

'(E) and edge attachment means for locking the abutting edges of said sector panel-s together to form an enclosure.

2. The inflatable structure defined in claim 1 in which the junction lines on said inner wall are spaced closer together over at least a portion of the :area of said inner wall than are the junction lines of said outer wall, whereby each sector panel upon inflation assumes a shape having compound curvature.

3. The structure defined in claim 1 in which said edge attachment means include (A) pairs of interleaved interlocking helical coil springs having opposite pitch directions,

(B) ,and a locking band (1) having a scalloped edge presenting edge-wise protruding points (2) and an opposite edge integrally joined to the outer face of each said sector panel adjacent the abutting edge thereof,

(C) onespring of each said pair being firmly secured to a protruding point of one said locking band and the other spring of said pair being firmly joined to an opposed point on a similar locking band secured to the abutting edge of the adjoining sector panel and aligned for interleaved engagement with its companion spring, and

(D) a flexible rod member positioned between the interleaved coils of said springs after engagement to secure them against disengagement,

whereby said double walled inflatable structure is firmly secured in its erected condition.

4. A self-supporting prefabricated double walled inflatable structure comprising in combination (A) a plurality of curved sector panels each having an inner wall and .an outer Wall;

(B) a plurality of substantially flat webs having elongated concentrically curved edges respectively joined to tabs extending along junction lines of the facing surfaces of said inner wall and said outer wall to form a successively arrayed plurality of adjoining longitudinallycurved inflatable cell chambers,

(C) with the Width of said inner wall corresponding to the length of its mating curved longitudinal edge of said web and the width of said outer wall correspondmg to the length of its mating curved longitudinal edge of said Web;

(D) end closure means joining the peripheries of said inner wall and said outer wall to form a cellular double-walled inflatable sector panel having an arcuate'ly curved shape upon inflation corresponding to the shape of said webs (E) and edge attachment means for locking the abutting edges of said sector panels together to form an enclosure.

5. The self-supporting prefabricated double walled inflatable structure defined in claim 4 wherein said webs are porous whereby air may pass slowly through said webs to adjoining cell chambers.

6. A self-supporting prefabricated double walled inflatable structure comprising in combination (A) a plurality of curved sector panels each having an inner wall and an outer wall of woven material;

(B) a plurality of substantially fiat Webs having elongated concentrically curved edges respectively joined to tabs interwoven with the walls along junction lines of the facing surfaces of said inner wall and said outer wall to form a successively arrayed plurality of adjoining longitudinally-curved inflatable cell chambers,

(C) with the width of said inner wall corresponding to the length of its mating curved longitudinal edge of said Web and the width of said outer wall corresponding to the length of its mating curved longitudinal edge of said Web;

(D) end closure means joining the peripheries of said inner Wall, said outer Wall and said webs to form a cellular double-walled inflatable sector panel having an arcuately curved shape upon inflation corresponding to the shape of said webs;

(E) and edge attachment means for locking the abutting edges of said sector panels together to form an enclosure.

7. A self-supporting prefabricated double-walled, in-

flatable structure comprising, in combination,

(A) a plurality of inflatable sector panels (1) each having inner and outer Walls of flexible material,

(a) said Walls being spaced when inflated,

(B) said panel walls being spaced 'by a plurality of webs attached along the web edges at wall junotion lines to form a plurality of inflatable cellular chambers,

(1) said webs being curved along their attached edges, (2) said webs being progressively shorter at the upper portion of each of said panels to provide a peaked upper portion on each panel,

(3) said junction lines being spaced closer together along the upper portion of said inner wall than for corresponding junction lines on said outer wall to provide a compound curvature at the upper portion in the shape of a portion of a dome,

(C) and edge attachment means for securing the abutting of edges of said sector panels together to form an inflatable, double-walled enclosure approximately circular in axial cross-section and having a domed top.

8. The inflatable structure defined in claim 7 wherein said junction lines have protruding tabs secured therealong, the corresponding tabs for the inner and outer wall junction lines being secured to said webs.

9. The inflatable structure defined in claim 8 wherein said tabs are interwoven with the flexible material of said walls along said junction lines.

References Cited by the Examiner UNITED STATES PATENTS 468,455 2/1892 Geissmann 1351 2,657,716 11/1953 Ford. 2,978,770 4/1961 Sperry et a1. 24-203 2,990,837 7/1961 Cushman 1351 3,024,796 3/1962 Bird 1351 3,034,154 5/1962 Silverstone 1351 X 3,055,379 9/1962 Fink 1351 FOREIGN PATENTS 513,389 11/1930 Germany.

HARRISON R. MOSELEY, Primary Examiner.

. REINALDO P. MACHADO, Examiner. 

1. A SELF-SUPPORTING PREFABRICATED DOUBLE WALLED INFLATABLE STRUCTURE COMPRISING IN COMBINATION (A) A PLURALITY OF CURVED SECTOR PANELS EACH HAVING AN INNER WALL AND AN OUTER WALL; (B) A PLURALITY OF JUNCTION LINES EXTENDING TRANSVERSELY ACROSS EACH SAID WALL, WITH THE WIDTH OF SAID OUTER WALL BEING GREATER THAN THE CORRESPONDING WIDTH OF SAID INNER WALL ALONG EACH JUNCTION LINE, (C)D BOTH SAID WALLS HAVING JUXTAPOSED TABS SECURED ALONG SAID JUNCTION LINES, EACH OF SAID JUXTAPOSED TABS BEING JOINED TOGETHER TO JOIN SAID WALLS IN SPACED RELATIONSHIP ALONG SAID JUNCTION LINE, (D) END CLOSURE MEANS JOINING THE PERIPHERIES OF SAID INNER WALL AND SAID OUTER WALL AND FORMING WITH THE FACING SURFACES OF SAID INNER WALL AND SAID OUTER WALL A SUCCESSIVELY ARRAYED PLURALITY OF ADJOINING LONGITUDINALLY-CURVED INFLATABLE CELL CHAMBERS JOINED TO FORM A CELLULAR DOUBLE-WALLED INFLATABLE SECTOR PANEL HAVING AN ARCUATELY CURVED SHAPE UPON INFLATION, (E) AND EDGE ATTACHMENT MEANS FOR LOCKING THE ABUTTING EDGES OF SAID SECTOR PANELS TOGETHER TO FORM AN ENCLOSURE. 